Lighting device



Oct. 26, 1937. H, SPANNiER 2,097,261

LIGHTING DEVICE Original Filed April 150, 1929 Jay 6 5 a i 0.0... .00005 4. 4 1 55 'l 2 53 933 53 13511 5? 53 {J mm, 57 M Jim up". 64 mm-u 56 k6/ 6/ I 57 5e 2/ 64 62 e0 W/ I 62 Patented Oct. 26, 1937 UNITED STATESPATENT OFFICE LIGHTING DEVICE Hans Joachim Spanner, Berlin, Germany 11Claims.

This application is a division of the application Serial No. 359,330,filed by applicant and Ulrich Doering on April 30, 1929, and on whichPatent No. 1,969,765 was granted August 14, 1934.

This invention relates to gas discharge devices, especially to thosedevices in which a gas discharge takes place in a glass tube and whichare suitable for illuminating purposes. More particularly the inventionrelates to such devices which operate with glowing and emittingcathodes.

The present invention has for its object the production of asatisfactory gas discharge device suitable for operation directly from alow voltage supply circuit. In order to more clearly explain theinvention, reference is made to the following description of difierentembodiments thereof taken in connection with the accompanying drawing inwhich Figure 1 is a longitudinal elevation partly in section of adischarge device, the external connections being shown in diagrammaticform;

Figure 2 is a longitudinal section of another form of gas dischargedevice with special means for changing from starting to runningoperation; and

Figure 3 is a longitudinal section of still another form of gasdischarge device.

The reference character N indicates a glass tube having electrodes l2and I3 positioned in the ends thereof. These electrodes are preferablyof a glowing and emitting type and may be maintained at a temperaturesufiiciently high ,to give the desired emissivity by the heating actionof the gaseous discharge itself. As examples of substances suitable forrendering the electrodes highly emissive may be mentioned barium,strontium, calcium, caesium and rubidum either in metallic form or ascompounds. Among the com- 40 pounds suitable for the purpose may bementioned phosphates and double silicates. The emissive substance mayhave associated therewith an anhydride of an amphoteric compound such asaluminum oxide or zirconium oxide which gives 45 greatly increasedresistance to disintegration.

These electrodes are connected through leadingin wires l4 and I5 toconductors l6 and ll of a suitable supply circuit. Current limiting orballast impedances l8 and H! are connected in the conductors l6 and H togive to the tube suitable operating characteristics, the gaseousdischarge path alone having a so-called negative characteristic.Auxiliary electrodes 20 and 2| may be positioned adjacent to theelectrodes l2 and I3 55 respectively, and are connected to theconductors H and I6 respectively through high resistances 22 and 23. Forobtaining special efiects fluorescing glass such as lead glass orscandium glass may be employed.

In operation, the line switch is closed and thereafter a discharge isset up between the main electrode l2 and the auxiliary electrode 20 atone end of the tube and between the main electrode I3 and the auxiliaryelectrode 2| at the other end of the tube. Because of the high value ofthe resistances 22 and 23, the current flow through these dischargepaths of short length is limited and the discharge is transferred forthe most part to the path which lies between the two main electrodes l2and i3.

In the form shown in Figure 2, electrodes 3| and 32 are positioned inthe ends of the tube ii and other electrodes such as 33 and 34 arepositioned in intermediate positions in the tube. The electrode 3| has aleading-in wire 35 connected to a line conductor 36 controlled by aswitch 31. The electrode 32 has a leading-in wire 38 connected to a lineconductor 39 in which is inserted a current limiting resistance 40. Theelectrode 33 has a leading-in wire 4| which is connected through oneside of a double pole switch 42 to the line conductor 39 and similarlythe electrode 34 has a leading-in wire 43 which is connected through theother side of the double pole switch to the line conductor 36. Theelectrodes 3|, 33, 34, and 32 may have positioned adjacent theretoauxiliary electrodes 44, 45, 46, and 4'! respectively. Each of theseelectrodes has a leading-in wire 48, 49, 50, and 5| which is connectedin each instance to the opposite line conductor from that to which itsadjacent main electrode is connected.

In operation, the line switch 31 is closed and also the double poleswitch 42. This places substantially the full line potential acrossadjacent main electrodes. Also substantially full line voltage isimpressed between each main electrode and its adjacent auxiliaryelectrode. Because of the shorter distance between each main electrodeand its auxiliary adjacent electrode, the discharge is first set upthrough these short paths, but because of the high resistance in serieswith these discharge circuits the discharge almost immediately passesover to the longer path between adjacent main electrodes. After the tubeis operating, the switch 42 may be opened and the discharge thereafterpasses from the electrode 3| to the electrode 32, all the gas dischargepaths 3|--33, 33-34, and 34-32 being in series.

In the form shown in Figure 3, the tube H is provided with a pluralityof chambers 53 extending at right angles from the main tube so as to beout of the main discharge path within the tube and in each of thesechambers is positioned an electrode which may comprise an outer emissivecoating or shell 54 within which is positioned a heating coil 55. Eachheating coil 55 has leading-in wires 56 and 51 which are connected toopposite conductors 58 and 59 of a supply circuit. A suitable resistance60 may be connected in each heating circuit to limit the current flowingin the heating coil or, if preferred, the heating coil may be sodesigned that the resistance may be dispensed with and the full linevoltage impressed directly on the heating coils. Each shell 54 isprovided with a leading-in wire 6! and these leading-in wires areconnected to the conductors 58 and 59 of the supply circuit, adjacentelectrodes being connected tothe opposite conductors. Each leading-inwire 6| is provided with a high impedance 52, which may be resistance ondirect current and resistance or inductance on alternating current, soas to give stability to a suitable current flow through the gaseousdischarge path. To facilitate starting of the gaseous discharge,auxiliary electrodes 63 may be provided adjacent toeach main electrode.Each auxiliary electrode 63,has a suitable leading-in wire 64 connectedthrough a high impedance 65 to the opposite side of the line from thatto which the adjacent main electrode is connected. The operation of thetube may be controlled by a suitable line switch 66 in the conductor 59.The starting of the gaseous discharge may also be materially assisted byconnecting adjacent electrodes by a conductive path, such as a filamentof wire, which may be in the form of a coil or helix as indicated at 61,.58, and 69.

The resistances of the coils 51, 68, and 59 may be so chosen that thecurrent drawn through the coils is very small but by a suitablearrangement and proportioning of these coils, the discharge may becaused to first start between an electrode and the adjacent portion ofthe coil, the discharge thereafter extending itself until it reachesfrom one main electrode to another. While both auxiliary electrodes andconductive connections between electrodes have been described as beingof assistance in starting the discharge, it is to be understood thatboth are not necessarily employed in every discharge tube, as one onlymay be suftlcient or even preferable under a given set of conditions.

In the operation of the form shown in Figure 3, the shells of theelectrodes are gradually heated by the passage of the current throughthe heating coils 55. The initial discharge first takes place either toan auxiliary electrode as 53, or to a portion of one of the conductivecoils connecting the electrodes. The conductive coils 61 and 69 may beomitted, if desired, as the discharge readily starts in adjacentsections of the tube after it has been set up in the middle portion sothat the conductive coil 68 in the middle section maybe sufiicient.

It will be seen from the foregoing description that simple and effectivemeans have been provided for such devices which enable them to be formedreadily into letter and into special bent and angular forms.

I claim:

1. In a radiant electrical discharge device which comprises an envelopepermeable to at least a part of the radiation from the discharge,

an ionizable filling therein adapted to carry the discharge, a pluralityof electrodes spaced apart therein, a cathode which comprises a metallicsupport and a coating thereon comprising an activating metal of theelectropositive group Ba, Sr, Ca, Cs, Rb, in a silicate material givenstrength and resistance to disintegration by heating, and in which theactivating coating also comprises a refractory amphoteric oxide besidesthe silica.

2. In a radiant electrical discharge device which comprises an envelopepermeable to at least a part of the radiation from the discharge, anionizable filling therein adapted to carry the discharge, a plurality ofelectrodes spaced apart therein, a cathode which comprises a metallicsupportand a coating thereon comprising an activating metal of theelectropositive group Ba, Sr, Ca, Cs, Rb, in a silicate material givenstrength and resistance to disintegration by heating, and in which theactivating coating also comprises zirconium oxide.

3. In a radiant electrical discharge device which comprises an envelopepermeable to at least a part of the radiation from the discharge,

an ionizable filling therein adapted to carry the discharge, a pluralityof electrodes spaced apart therein, a cathode which comprises a metallicsupport and a coating thereon comprising an'activating metal of theelectropositive group Ba, Sr, Ca, Cs, Rb, in a silicate material givenstrength and resistance to disintegration by heating, and in which theactivation coating is formed from a double silicate of the activatingmetal. 1

4. In a radiant electrical discharge device which comprises an envelopepermeable to at least a part of the radiation from the discharge, anionizable filling therein adapted to carry the discharge, a plurality ofelectrodes spaced apart therein, a cathode which comprises a metallicsupport and a coating thereon comprising an activating metal of theelectropositive group Ba, Sr, Ca, Cs, Rb in a phosphate material givenstrength and resistance to disintegration by heating.

5. In a radiant electrical discharge device as defined in claim 4 acathode as therein defined in which the activating coating comprisesi'ree metal of said electro-positive group.

6. A radiant electrical discharge device comprising an envelopepermeable to at least a part of the radiation from the discharge, agaseous filling therein adapted to carry the discharge, a plurality ofelectrodes spaced therein, and a spiral conductor between theelectrodes, close to the wall of said envelope, surrounding thedischarge.

7. A radiant electrical discharge device comprising anenvelope'permeable to at least a part of the radiation from thedischarge, a gaseous filling therein adapted to carry the discharge, aplurality of spaced electrodes therein, and a high resistance thermionicconductor connected between said electrode and extended for asubstantial distance along and near the inner surface 01' tive to theprincipal electrode, than upon any 7 atoms:

part of said conductor which is equally near the principal electrode,whereby to protect said con-= ductor against injury by arcing from theprincipal electrode.

9. The combination of a radiant electrical discharge device comprisingan envelope permeable to at least a part of the radiation from thedischarge, a gaseous filling therein of material adapted to provide agaseous atmosphere for the discharge, a plurality of electrodespositioned therein, at least two of which are far apart and at least twoof which are positioned intermediate said first two along the path ofthe discharge, and means for energizing a discharge therein comprising asource of potential, means for connecting one side of said source toalternate electrodes and for connecting the other side of said source tothe other alternate electrodes in the discharge device, and means in theconnections to the intermediate electrodes for disconnecting saidintermediate electrodes after the discharge is started, whereby thedischarge may continue thereafter directly between the electrodes whichare far apart.

10. A radiant electrical discharge device com prising an envelopepermeable to at least a part of the radiation from the discharge, afilling therein adapted to provide a gaseous atmosphere for thedischarge, a plurality of electrodes spaced therein, and a highresistance thermionic conductor extended along the space between theelectrodes and adapted to be heated to thermionic temperature by thecurrent passing therethrough, and a source of current in circuit withsuch conductor adapted to provide current sufllcient to heat theconductor to thermionic temperature and at a potential greater than thestriking potential of ,a discharge between the ends of said conductor inthe ionized filling, whereby the conductor upon reaching a temperatureof thermionic emission sufiicient to ionize the gas automatically shortcircuits itself by initiating a discharge at lower potential in the gas.

11. A radiant electrical discharge device as defined in claim 10 inwhich one of the electrodes is an activated cathode and the thermionicconductor is connected to opposite electrodes, whereby substantially thefull potential imposed on the principal electrodes for starting of thedischarge is imposed upon the high resistance conductor andthe automaticshort-circuiting of the con ductor by a discharge establishes thedischarge immediately and directly between the principal electrodes.

HANS JOACHIM SPANNER.

